Magnetoelastic effect characterizes the change of materials' magnetic properties under mechanical deformation, which is conventionally observed in some rigid metals or metal alloys. Here we show ...magnetoelastic effect can also exist in 1D soft fibers with stronger magnetomechanical coupling than that in traditional rigid counterparts. This effect is explained by a wavy chain model based on the magnetic dipole-dipole interaction and demagnetizing factor. To facilitate practical applications, we further invented a textile magnetoelastic generator (MEG), weaving the 1D soft fibers with conductive yarns to couple the observed magnetoelastic effect with magnetic induction, which paves a new way for biomechanical-to-electrical energy conversion with short-circuit current density of 0.63 mA cm
, internal impedance of 180 Ω, and intrinsic waterproofness. Textile MEG was demonstrated to convert the arterial pulse into electrical signals with a low detection limit of 0.05 kPa, even with heavy perspiration or in underwater situations without encapsulations.
The magnetoelastic effect-the variation of the magnetic properties of a material under mechanical stress-is usually observed in rigid alloys, whose mechanical modulus is significantly different from ...that of human tissues, thus limiting their use in bioelectronics applications. Here, we observed a giant magnetoelastic effect in a soft system based on micromagnets dispersed in a silicone matrix, reaching a magnetomechanical coupling factor indicating up to four times more enhancement than in rigid counterparts. The results are interpreted using a wavy chain model, showing how mechanical stress changes the micromagnets' spacing and dipole alignment, thus altering the magnetic field generated by the composite. Combined with liquid-metal coils patterned on polydimethylsiloxane working as a magnetic induction layer, the soft magnetoelastic composite is used for stretchable and water-resistant magnetoelastic generators adhering conformably to human skin. Such devices can be used as wearable or implantable power generators and biomedical sensors, opening alternative avenues for human-body-centred applications.
Taking advantage of the coupling effect of contact electrification and electrostatic induction, triboelectric nanogenerators can effectively convert various forms of ambient mechanical energy into ...electricity, and therefore have attracted much attention, with broad applications in energy harvesting, active sensing, and biomedical therapy, which are anticipated to be an indispensable component in the era of the Internet of things. To improve the mechanical-to-electrical conversion, various strategies have been reported to engineer the materials used at the nanoscale with physical, chemical, biological, and hybrid approaches. These strategies to enhance the output performance and extend the applications of triboelectric nanogenerators are comprehensively reviewed and summarized in this article. Furthermore, perspectives are also discussed in depth, with an emphasis on future research directions to further advance developments within the field.
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Triboelectric nanogenerators (TENGs) may provide a sustainable and pervasive energy solution in the era of “the Internet of Things.” Nanoengineering approaches to enhance the mechanical-to-electrical conversion and extend the applications of TENGs, including physical, chemical, biological, and hybrid strategies, are comprehensively reviewed by Zhou et al. Future research directions and opportunities are also discussed.
A case study of the MJO event observed during January and February 2017 is conducted to understand its propagation through the Maritime Continent (MC) region. Ensemble cloud-permitting numerical ...simulations are performed to test the effects of the islands over MC on this MJO event. The control simulation reasonably captures the large-scale mean state, eastward propagation and diurnal cycle over islands of this MJO event. Sensitivity experiments are conducted to test the impact of topography, friction, and land-sea contrast on this MJO event. Eliminating the topography around the MC region leads to reduced precipitation over the islands while changes in eastward propagation are small. When friction is further removed, results are similar except that the low-level wind is stronger, and the MJO precipitation propagation is not essentially different. Land-sea contrast is further eliminated by replacing land with ocean, and the MJO is stronger and displays smoother eastward propagation. Diagnosis of moist static energy budget indicates that both the surface flux feedback and horizontal advection (especially the zonal advection) are greatly strengthened without land-sea contrast, which enhance the convection over the sea and facilitate the eastward propagation of the MJO.
The next‐generation wearable biosensors with highly biocompatible, stretchable, and robust features are expected to enable the change of the current reactive and disease‐centric healthcare system to ...a personalized model with a focus on disease prevention and health promotion. Herein, a muscle‐fiber‐inspired nonwoven piezoelectric textile with tunable mechanical properties for wearable physiological monitoring is developed. To mimic the muscle fibers, polydopamine (PDA) is dispersed into the electrospun barium titanate/polyvinylidene fluoride (BTO/PVDF) nanofibers to enhance the interfacial‐adhesion, mechanical strength, and piezoelectric properties. Such improvements are both experimentally observed via mechanical characterization and theoretically verified by the phase‐field simulation. Taking the PDA@BTO/PVDF nanofibers as the building blocks, a nonwoven light‐weight piezoelectric textile is fabricated, which hold an outstanding sensitivity (3.95 V N−1) and long‐term stability (<3% decline after 7,400 cycles). The piezoelectric textile demonstrates multiple potential applications, including pulse wave measurement, human motion monitoring, and active voice recognition. By creatively mimicking the muscle fibers, this work paves a cost‐effective way to develop high‐performance and self‐powered wearable bioelectronics for personalized healthcare.
To mimic muscle fibers, polydopamine is dispersed into the electrospun barium titanate/polyvinylidene fluoride nanofibers to enhance the interfacial‐adhesion, mechanical strength, and piezoelectric properties. The muscle‐fiber‐inspired nonwoven piezoelectric textile is demonstrated for pulse wave measurement, human motion monitoring, and active voice recognition.
Abstract
Polymer-ceramic piezoelectric composites, combining high piezoelectricity and mechanical flexibility, have attracted increasing interest in both academia and industry. However, their ...piezoelectric activity is largely limited by intrinsically low crystallinity and weak spontaneous polarization. Here, we propose a Ti
3
C
2
T
x
MXene anchoring method to manipulate the intermolecular interactions within the all-
trans
conformation of a polymer matrix. Employing phase-field simulation and molecular dynamics calculations, we show that OH surface terminations on the Ti
3
C
2
T
x
nanosheets offer hydrogen bonding with the fluoropolymer matrix, leading to dipole alignment and enhanced net spontaneous polarization of the polymer-ceramic composites. We then translated this interfacial bonding strategy into electrospinning to boost the piezoelectric response of samarium doped Pb (Mg
1/3
Nb
2/3
)O
3
-PbTiO
3
/polyvinylidene fluoride composite nanofibers by 160% via Ti
3
C
2
T
x
nanosheets inclusion. With excellent piezoelectric and mechanical attributes, the as-electrospun piezoelectric nanofibers can be easily integrated into the conventional shoe insoles to form a foot sensor network for all-around gait patterns monitoring, walking habits identification and Metatarsalgi prognosis. This work utilizes the interfacial coupling mechanism of intermolecular anchoring as a strategy to develop high-performance piezoelectric composites for wearable electronics.
Supercapacitors (SCs) have shown great potential for mobile energy storage technology owing to their long‐term durability, electrochemical stability, structural simplicity, as well as exceptional ...power density without much compromise in the energy density and cycle life parameters. As a result, stretchable SC devices have been incorporated in a variety of emerging electronics applications ranging from wearable electronic textiles to microrobots to integrated energy systems. In this review, the recent progress and achievements in the field of stretchable SCs enabled by low‐dimensional nanomaterials such as polypyrrole, carbon nanotubes, and graphene are presented. First, the three major categories of stretchable supercapacitors are discussed: double‐layer supercapacitors, pseudo‐supercapacitors, and hybrid supercapacitors. Then, the representative progress in developing stretchable electrodes with low‐dimensional (0D, 1D, and 2D) nanomaterials is described. Next, the design strategies enabling the stretchability of the devices, including the wavy‐shape design, wire‐shape design, textile‐shape design, kirigami‐shape design, origami‐shape design, and serpentine bridge‐island design are emphasized, with the aim of improving the electrochemical performance under the complex stretchability conditions that may be encountered in practical applications. Finally, the newest developments, major challenges, and outlook in the field of stretchable SC development and manufacturing are discussed.
Recent advances in the development of stretchable supercapacitors from low‐dimensional nanomaterials are reviewed, with an emphasis on the aspects of electrode materials, design strategies, and fabrication and performance of devices. The challenges and prospective of the stretchable supercapacitors are also discussed, providing fundamental insight and offering useful guidelines for future design of new high‐performance stretchable energy devices for wearable and medical applications.
Interfacing with the human body, wearable and implantable bioelectronics are a compelling platform technology for healthcare monitoring and medical therapeutics. However, clinical adoption of these ...devices is largely shadowed by their weakness in humidity resistance, stretchability, durability, and biocompatibility. In this work, we report a self-powered waterproof biomechanical sensor with stretchability up to 440% using the giant magnetoelastic effect in a soft polymer system. By manipulating the magnetic dipole alignment, the sensor achieved a particularly broad sensing range from 3.5 Pa to 2000 kPa, with a response time of ∼3 ms. To validate the excellent performance of the magnetoelastic sensor in biomonitoring, both ex vivo porcine heart testing and in vivo rat model testing were performed for cardiovascular monitoring and heart disease diagnosis. With the obtained sensing data, we have successfully detected ventricular arrhythmia and ventricular fibrillation in the Sprague–Dawley rat model. Holding a collection of compelling features, including minimal hysteresis, ultrawide sensing range, waterproofness, and biocompatibility, the magnetoelastic sensor represents a unique platform technology for self-powered biomonitoring in both wearable and implantable manners.
Abstract
DNA origami technology enables the precise assembly of well-defined two-dimensional and three-dimensional nanostructures with DNA, an inherently biocompatible material. Given their ...modularity and addressability, DNA origami objects can be used as scaffolds to fabricate larger higher-order structures with other functional biomolecules and engineer these molecules with nanometer precision. Over the past decade, these higher-order functional structures have shown potential as powerful tools to study the function of various bio-objects, revealing the corresponding biological processes, from the single-molecule level to the cell level. To inspire more creative and fantastic research, herein, we highlight seminal works in four emerging areas of bioapplications of higher-order DNA origami structures: (1) assisting in single-molecule studies, including protein structural analysis, biomolecule interaction analysis, and protein functional analysis, (2) manipulating lipid membranes, (3) directing cell behaviors, and (4) delivering drugs as smart nanocarriers. Finally, current challenges and opportunities in the fabrication and application of DNA origami-based functional structures are discussed.
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